The aircraft manufacturer Boeing is reported to be investigating anti-gravity research. But our science correspondent Dr David Whitehouse says jumbo jets are unlikely to start floating off the ground any time soon.

What has fired the interest of Boeing?

According to company documents seen by the respected journal Jane's Defence Weekly, Boeing is intrigued by the Russian of Russian Dr Eugene Podkletnov. It wants to see if it really is possible to build an "impulse gravity generator".

An object held above the ring lost about 2% of its weight. The pull of gravity on the object was reduced, he claims.

When did Dr Podkletnov do this?

It seems that the first time was at a Finnish university in 1992. However, the research paper that described the results was submitted to a scientific journal but then withdrawn. The same happened in 1996 when news of the paper's imminent publication leaked. However, Dr Podkletnov has continued to work on his ideas and is reported to have seen similar effects in his studies.

Has the experiment been repeated by others?

Several teams have tried but none has seen the same thing. The American space agency Nasa tried but said it couldn't find any effect.

Is anti-gravity possible?

The vast majority of the world's qualified scientists would fervently say that it is not. If it were possible to shield something from the force of gravity it would mean a rewrite of the most fundamental, cherished, and rigorously tested laws of physics. Most would put it alongside a perpetual-motion machine. That is, impossible.

But George Muellner of Boeing has been quoted as saying that the science of the antigravity device appeared to be valid and possible. Why did he say that?

There are three possibilities. Perhaps he knows something the rest of the world's physicists don't, or he does not understand the laws of physics, which would be highly surprising for a man in his position, or he has been misquoted.

If it were possible what would be the outcome?

We could build spacecraft that would not need any rockets to power them. Aircraft would not need engines and could be any size and stay up indefinitely using no fuel. Supporters have claimed military and medical applications as well.

Have I heard this before?

If you read HG Wells, yes. In his First Men On The Moon, he writes of an eccentric inventor called James Cavor who creates a substance called Cavorite that repels gravity. Coating a capsule with it makes the vehicle fly up towards the Moon.

But is not history full of geniuses who changed the world after their colleagues had dismissed them as crazy?

There are not as many of these as you might think. Besides, just because a few geniuses have been laughed at in the past does not mean that every one who is laughed at today will turn out to be a genius in the future.